The present invention relates to self polymerisation products of diamino anthracenes (DAA) and polymerisation of DAA with diiminoanthracenes (DIA). In particular, the invention relates to homopolymers or co-polymers of 9,10 diaminoanthracene or substituted DAA or DIA or substituted DIA. The polymerisation products may be polymers or oligomers (e.g. of 2 to 12 or 15 repeat units) and the processes of the present invention enables homopolymers and co-polymers to be made with many variations in structure and in the substituents which are attached to the anthracene backbone, but with little variation in the backbone itself. The polymers and co-polymers can be expected on reduction to produce materials which are electroconductive.
They may also be sufficiently transparent to be used in thin film applications where they may be used as transparent coatings, used extensively in displays, e.g. electroluminescent and liquid crystal displays and to some extent in electromagnetic shielding windows. The polymers and copolymers disclosed herein can be used in antistatic applications.
Polymers of aniline and applications thereof have been known for many years. Poly (1-aminoanthracene) (P1-AA hereafter) has also been described (Takakazu Yamamoto et al., Macromolecules, 1993, 26, pages 6992-6997). These polymers have similar structures to poly(aniline) and are dark coloured, varying from bluish-black, brown to brown-black powders. Yamamoto states P1-AA has conductivity of the order of 1xc3x9710xe2x88x924 S cmxe2x88x921. P1-AA is stated by Yamamoto to be soluble in organic solvents such as HCOOH, DMF, DMSO and NMP, slightly soluble in CHCl3 and THF, and insoluble in CH3OH, C2H5OH, CH3CN, benzene and toluene. Yamamoto gives no indication of the transparency of P1-AA.
The applicants are also aware of two articles namely A. Everaerts et al., Polym. Prepr. (J. of Polymer Science; Part A: Polym. Chem.) 24 (7)pp 1703-16 (1986) (hereafter Everaerts) and P. A. Williams et al, Macromolecules 26 (21) pp5820-1 (1993) (hereafter Williams).
The present inventors have been seeking to develop a conductive polymer or oligomer of sufficient transparency to enable it to be used where light transmission as well as conductivity is required, and in addition solubility which would facilitate fabrication into useful structures, such as films, by solvent methods. In contrast to P1-AA we have discovered surprisingly that certain polymerisation products of 9,10 diaminoanthracene are sufficiently transparent and soluble to be useful electroconductive polymers.
These products may exhibit a particular advantage over the transparent Indium Tin Oxide (ITO) films currently employed in transparent coatings. The ITO coatings lose most or all of their electroconductivity if the surface is bent. However, the products according to the present invention can be expected to maintain their electroconductivity even when bent.
In addition the present inventors wished to devise a procedure by which polymers could be provided in which the polymer backbone was constant or subject to little variation and significant flexibility was provided for varying the substitution on the backbone.
According to one aspect of the invention a method of production of a homopolymer or copolymer or homo-oligomer or co-oligomer product is characterised in that the product is obtained by condensation by fusion in a sealed vessel or space of a diaminoanthracene, substituted or not, optionally with a diiminoanthracene substituted or not, in the absence of any solvent and in the absence of anthraquinone substituted or not.
According to another aspect of the present invention, there is provided a polymeric or oligomeric product obtainable from the reaction of an aromatic diamine with itself or a substituted form thereof or with a diimino version or a substituted version thereof, characterised in that the diamine is a diamino anthracene which is substituted or is not substituted, and the diimine is diiminoanthracene which is substituted or not, and in that the reaction is by melting under vacuum, in the absence of solvent and in the absence of anthraquinone whether substituted or not.
The substitution may be such that the product is a homopolymer or homo-oligomer, or the substitution may be such that the product is a co-polymer or a co-oligomer.
The diaminoanthracene is preferably a 9,10-diaminoanthracene, which may be substituted or not.
The sole reactant may be DAA or the only reactants may be DAA and DIA,
or the only reactants may be one or more substituted DAAs and DAA.
or the only reactants may be substituted DAAs which may be the same or different.
or the only reactants may be one or more substituted DAAs and DIA.
or the only reactants may be DAA and one or more substituted DIAs.
or the only reactants may be one or more substituted DAAs and one or more substituted DIAs.
The ratio of DAA to DIA may be in the range 5:1 to 1:5, preferably in the range 3:1 to 1:3, and more preferably in the range 2:1 to 1:2.
The product produced by the method of the present invention preferably has the general formula I (see FIG. 10 of the accompanying drawings) 
where, R1 may be the same as or different to R1xe2x80x2, which may be the same as or different to R2, which may be the same as or different to R2xe2x80x2 and each of R1, R1xe2x80x2, R2, and R2xe2x80x2 is a hydrogen atom or xe2x80x94CH3, CH3CH2xe2x80x94, xe2x80x94OCH3, xe2x80x94OCH2CH3, xe2x80x94CH2OCH3, xe2x80x94CH2OCH2CH2OCH3, methoxyethoxyethoxymethyl, aryloxymethyl, phenyl, Cl, Br, CN or NO2, xe2x80x94CH2COORxe2x80x2xe2x80x3 or xe2x80x94CH2NHCORxe2x80x2xe2x80x3 (where Rxe2x80x2xe2x80x3 is C1-C6 alkyl or a phenyl or biphenyl group), or a C1-C5 alkyl group, or an aryl group e.g. a benzyl group, or an xe2x80x94SO3H group or a hydroxyl group or a C1-C5 alkoxy group or an H2PO3 group, and R1 and R1xe2x80x2 are different to R2 and R2xe2x80x2 and n is an integer ranging from 2 to 100 preferably 5 to 100, more preferably 6-20.
Alternatively the product may have the general formula I 
where, R1 may be the same as or different to R1xe2x80x2, and each of R1 and R1xe2x80x2 is a hydrogen atom or xe2x80x94CH3, CH3CH2xe2x80x94, xe2x80x94OCH3, xe2x80x94OCH2CH3, xe2x80x94CH2OCH3, xe2x80x94CH2OCH2CH2OCH3, methoxyethoxyethoxymethyl, aryloxymethyl, phenyl, Cl, Br, CN or NO2, xe2x80x94CH2COORxe2x80x2xe2x80x3 or xe2x80x94CH2NHCORxe2x80x2xe2x80x3 (where Rxe2x80x2xe2x80x3 is C1-C6 alkyl or a phenyl or biphenyl group), and R2 may be the same or different to R2xe2x80x2 and each of R2 and R2xe2x80x2 is a hydrogen atom or a C1-C5 alkyl group, or an aryl group e.g. a benzyl group, or an xe2x80x94SO3H group or a hydroxyl group or a C1-C5 alkoxy group or an H2PO3 group, and R1 and R1xe2x80x2 are different to R2 and R2xe2x80x2 and n is an integer ranging from 2 to 100 preferably 5 to 100, more preferably 6-20.
R1 may be the same as R1xe2x80x2 but may be different from R2 and R2xe2x80x2 and R2 and R2xe2x80x2 may be the same;
or R1 may be the same as R1xe2x80x2 and as R2 and R2xe2x80x2 but is not hydrogen;
or R1 may be different from R1xe2x80x2 and R2 may be different from and R2xe2x80x2 and R1 and R1xe2x80x2 may both be different from R2 and R2xe2x80x2;
or that R1 and R2 are not hydrogen and R1 and R2xe2x80x2 are not the same.
The DAA may be substituted with a single substituent e.g. a C1-C5 alkyl, an aryl e.g. a benzyl group, an xe2x80x94SO3H or xe2x80x94OH, or C1-C5 alkoxy, or aryloxy, e.g. phenoxy or substituted phenoxy or biphenyloxy group or an H2PO3 group or with more than one substituent.
In a preferred embodiment of the invention the fusion reaction is carried out in a sealed space e.g. a sealed ampoule containing equimolar proportions of 9,10-diaminoanthracene and 9,10-diiminoanthracene e.g. at 200xc2x0 C. for 4 hours under vacuum as shown in reaction Scheme 1 given in the drawings as FIG. 7. 9,10-diiminoanthracene may be synthesised by aerial oxidation of 9,10-diaminoanthracene e.g. in benzene e.g. at 65xc2x0 C. for 30 minutes. This compound is more stable than its precursor, 9,10-diaminoanthracene.
In reaction Scheme 1 the amino groups of 9,10-diaminoanthracene react as nucleophiles with the diimine groups 9,10-diiminoanthracene with displacement of ammonia. Ammonia can be smelt and detected when the fusion tube is opened.
The use of a vacuum is necessary to avoid oxidation of the monomers to anthraquinone which is liable to occur in air. Reaction in a sealed space is not sufficient because the build up of ammonia is liable either to rupture the space e.g. a sealed ampoule or to suppress the progress of the reaction.
Sealed ampoules evacuated to about 10xe2x88x921 mm Hg (0.1 mm) have been found effective to allow reaction to occur. However it is preferred that continuous evacuation is used so as to ensure removal of the liberated ammonia, which will drive the reaction towards completion, as well as ensuring that the pressure of oxygen is minimised.
Vacuum of the order of 10xe2x88x921 to 10xe2x88x924 mm Hg may be used, preferably 10xe2x88x921 to 10xe2x88x923 mmHg. At vacuums greater than 10xe2x88x924, e.g. 10xe2x88x925 the compounds are liable to evaporate. The fused product, a dark brown, hard solid may be collected using acetone in which almost all the product dissolves. However, a very small quantity (5-10% by weight) is insoluble and may be collected by filtration. This is thought to be higher molecular weight long chain polymeric products.
The fusion method of the present invention has the advantage of simplicity and also versatility. The reaction has been observed to give oligomeric products ranging from dimer to heptamer.
Further, it has also been found that there are long chain polymeric products having molecular weights up to 8000.
The polymerisation may also be carried out starting from a solution of DAA or derivatives thereof or from solutions of the monomers (e.g. DAA and DIA or derivatives thereof) which can be mixed in the proportions needed to give the desired proportions of the molecules.
This gives homogenous mixtures. The solution can be deposited on a desired substrate and heated under vacuum. The solvents will first evaporate off and then the monomer(s) will melt and polymerise.
For devices which are to operate using voltages in the range up to 20 volts e.g. 3 to 20 volts a conductive coating will be needed on the transparent substrate. Such a coating could be an ITO layer, or a fluorine doped tin oxide layer or other appropriately conductive transparent layer.
The invention thus extends to transparent substrates provided with an electrically conducting first layer on at least one surface and on that first layer a second layer of conducting material in accordance with the present invention. The said first layer can be provided by a different electrically conducting layer e.g. of ITO. Alternatively the first and second layers can be afforded by a single layer of a material of the present invention or separate layers of a material of the present invention.
A further layer or layers can be provided on top of the said second layer. Preferably for use in electro luminescent display devices the substrate and each layer will have adequate transmission properties to pass light of the wavelength being used. For example they are preferably transparent to visible light.
The third layer is typically a layer of an electron transport or emitting material such as aluminium quinolate (see formula 15 in the accompanying drawings). Examples of other suitable materials are given in the article by Ching W. Tang in xe2x80x9cInformation Displayxe2x80x9d 10/96 at pages 16 to 19.
As alternative procedures to dissolution and filtration such as continuous extraction and chromatography may be used to separate the oligomers formed. The fusion reaction may be carried out at different times and temperatures to increase the yield of long chain polymeric products. In addition, the fusion reaction of substituted versions of 9,10-diaminoanthracene and 9,10-diiminoanthracene, may be carried out to give a range of polymeric products.
One such scheme is as set out in the Reaction Scheme 2 shown as FIG. 8 in the accompanying drawings.
In Reaction Scheme 2, R1 and R2 may be the same or different and may be a hydrogen atom or xe2x80x94CH3, CH3CH2xe2x80x94, xe2x80x94OCH3, xe2x80x94OCH2CH3, xe2x80x94CH2OCH3, xe2x80x94CH2OCH2CH2OCH3, methoxyethoxyethoxymethyl, aryloxymethyl, phenyl, Cl, CN or NO2, xe2x80x94CH2COORxe2x80x2xe2x80x3 or xe2x80x94CH2NHCORxe2x80x2xe2x80x3 (where Rxe2x80x2xe2x80x3 is C1-C6 alkyl or a phenyl or biphenyl group), or a C1-C5 alkyl group, or an aryl group e.g. a benzyl group, or an xe2x80x94SO3H group or a hydroxyl group or a C1-C5 alkoxy group or an H2PO3 group, and n is an integer ranging from 2 to 100 preferably from 10 to 100, preferably 50 to 80, e.g. about 70.
The present invention also extends to a transparent electroconductive coating or a static shielding material comprising a product made by the method of the present invention.
The invention enables the production, by a simpler and cleaner route of polymeric products having the general formula (I) as discussed above.
Polymers with lower values of n, e.g. 2 to 10, or 2-15 which may be referred to as oligomers, will have higher solubility but may have lower heat stability than the polymers.
The products of the invention can be expected on partial reduction to produce materials which are conductive and therefore may find uses in thin film technology, as EMI, RFI (electro magnetic interference, radio frequency interference) shielding materials and in display systems, such as electroluminescent and liquid crystal display systems as a transparent electrode.
The oligomers or polymers disclosed herein can be used even without reduction in antistatic applications.
Such reduced polymeric products may be used with other polymers (or binders). The polymeric productxe2x80x94binder blend may comprise from 5 to 70% by weight of the polymeric product and from 95 to 30% by weight of the other polymer. The polymer with which the polymeric product is blended may be, for example, poly(vinyl chloride), polyethylene, polypropylene, polystyrene, nylon, poly(acrylonitrile-butadiene-styrene), poly(ethylene terephthalate), poly(ethylene oxide), polymethyl methacrylate, polyether sulphone, polyether ketone, polytetrafluoroethylene.
These blends may have sufficient conductivities to give good antistatic properties at the lower concentrations of polymeric product. At the higher concentrations the blends may possess levels of conductivity which may be useful for shielding.
Furthermore, the polymeric product imparts the required electrical property to the blend immediately and unlike alkylammonium salts, do not need moisture to impart conductivity to the polymer.
Conductive adhesives may be formulated using the polymeric product of the present invention.
The polymeric product of the present invention may also be directly deposited chemically or electrochemically onto and/or impregnated into a porous polymer film such as poly(vinyl chloride), poly(carbonate) or poly(propylene). The surface of a component so formed can be permanently conductive and may have good antistatic properties.
This surface may be painted with coloured dyes or pigments and the colour modified without impairing the antistatic properties. This method may enable antistatic floors and mats to be fabricated from the composites.
Furthermore, non-conductive materials such as talc or mica may be coated with the polymeric product of the invention either chemically or electrochemically. Such coated powders may be useful as fillers for the formation of conductive polymer composites.
Furthermore, solutions of the solvent soluble polymeric product may be sprayed onto a non-conducting surface which can then become conductive on evaporation of the solvent therefrom. The resulting film can be used in display devices.
The polymeric products produced may be dissolved in organic solvents such as acetone, dimethylformamide, dimethylsulphoxide, and N-methyl pyrrolidone, and may also be processable into thin films.
It is also possible to partially reduce the produced polymeric products with a suitable reducing agent, for example sodium cyanoborohydride, sodium borohydride, sodium borohydride-boron trifluoride etherate, lithium aluminium hydride, hydrazine and dithionites. These partially reduced polymeric products may have a lighter colour and sufficient electroconductivity to be used in transparent thin film technology. It is also possible to dope these polymeric products with suitable acid dopants, for example camphorsulphonic acid, 5-sulphosalicylic acid, para-toluenesulphonic acid, trifluoromethanesulphonic acid (triflic acid), methanesulphonic acid, trifluoroacetic acid, hydrochloric acid and sulphuric acid. This may enhance the electroconductivity of the polymeric product.